The Effects of Hot Springs on Cognitive Function

Abstract

The effectiveness of thermal stimulation against dementia has been reported in Finnish saunas. In a prospective study of 2,315 healthy men, the risk of dementia was reduced by 22％ by sauna bathing 2-3 times a week and 66％ by sauna bathing 4-7 days a week compared to sauna bathing once a week. It is considered that the heat improves endothelial function, increases angiogenesis, and reduces inflammation, preventing a decrease in cerebral blood flow. It has also been reported that heat reduces the excessive phosphorylation of tau protein, which is associated with dementia. A cohort study of 10,147 healthy people aged 65 years or older in Japan, who had bathing frequency recorded, also reported that the incidence of dementia was lower in those who bathed 7 times or more per week than those who bathed 0-1 times per week. Both hot springs and saunas have a body temperature rise of 38.5℃ or more, and this heat stimulation increases the NK cell activity, which are cell surveillance mechanism, and heat shock proteins, which manage and repair proteins, and defense mechanisms are activated. It is considered that hot springs bathing can suppress the increase and deposition of abnormal proteins associated with dementia by enhancing the heat stimulation defense mechanism due to the increase in body temperature.